What is Shear: Definition and 621 Discussions

Shear stress, often denoted by τ (Greek: tau), is the component of stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. Normal stress, on the other hand, arises from the force vector component perpendicular to the material cross section on which it acts.

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  1. C

    Tensile and shear stress in 10mm rivet

    Homework Statement A load P of 3kN is applied to the tensile member shown and is carried at the joint by a single rivet. The angle of the shear joint is 45 degrees to the axis of the load. Calculate the tensile and shear stresses in a 10mm diameter rivet Homework EquationsThe Attempt at a...
  2. F

    Shear stress resisted by a bolt

    Homework Statement In this problem , why the author use (30x10^3) /s = VQ / I only ? Shouldnt it be 4(30x10^3) /s = VQ / I Homework EquationsThe Attempt at a Solution I said so , because the board at the centered is connected by 4 bolts , 2 on the left and 2 on the right . The faces on the...
  3. F

    Question about shear flow / stress

    Homework Statement For QB , why shouldn't the QB = red part only ? Homework EquationsThe Attempt at a Solution Is there anything wrong with the solution given ? Since When we 'cut ' the boards , the b is the red part which in contact with the other board , right ? [/B]
  4. D

    Shear Stress, Area of Projection

    I am learning about shearing stress, and I am a little confused about the area of projection mentioned in my book. When it introduces it, it shows a plate with a rivet through it. The plate is of thickness t, and the diameter of the rivet, d. It shows the plate and the rivet cut in half by a...
  5. F

    Shear stress at the boundary of beam

    Homework Statement We all know that $$\tau = VQ/ It $$ how to determine the shear stress at **G** ? I'm having problem of finding Ay centroid if the solid that i found earlier is y = 98.5mm There's a dashed line from G to the bottom . It's making me confused . for Q , should i consider the...
  6. F

    Is the Shear Flow Direction Incorrect in Preventing Beam Twisting?

    In the figure , we can notice that the moment due to Pe is counterclokwise , but moment due to shear flow is also counterclockwise , How can the Pe prevent the twisting of the beam ? Or is the direction of the shear flow wrong ? Should it flow from the below to the top ?
  7. F

    Sign convention of shear stress confusion

    Homework Statement In my book , i was told that when the shear stress turn a plane of element clockwise , then the shear stress is positive , In this question , we can notice the shear stress of 40 will turn the plane clockwise , why the author plot the stress at A = (80,-40) ? Shouldn't it be...
  8. F

    Angle of principal stress vs maximum shear stress

    Homework Statement I'm having problem with the angle of $$theta_s1$$ . My ans is +35 (as in my working) , but the ans provided is $$theta_s1$$ = -55[/B] Homework EquationsThe Attempt at a Solution As in the picture posted
  9. F

    Maximum shear stress in Mohr's circle

    Homework Statement I am not sure how to get the maximum shear force in mohr's circle [/B] Homework EquationsThe Attempt at a Solution To get the ##\theta_s max ## , we have to 'turn' the B to ##\tau_{max}## , right ? So , it should be like this ( in the figure , orange arrow) ? Am i right ...
  10. F

    Shear stress at different points of beam

    Homework Statement i'm not sure how to calculate the shear stress at point F and point G . I know that shear stress has formula of $$ \tau = VQ/It $$ The maximum shear force that i calculated earlier is V = 205kN , Ixx = 2.1x10^-4 for Q at $$\tau$$ at F , i have...
  11. F

    Shear force at different parts of beam

    Homework Statement i know this question can't be done(since the location of point where the tau 1 and tau2 are measured are unknown) , but i want just want to check whether my concept is correct or not . we know that the shear stress has formula of $$\tau = VQ / It$$ , the question want the...
  12. F

    Twisting at shear center / centroid

    In the notes , the author stated that when the force is applied through the centorid of cross section , the channel will bend and twist. but , on the second page , the author stated that the shear center lies on an axis of symmetry of member's cross sectional area... So, i am confused whether...
  13. F

    Twisting at shear center / centroid

    Homework Statement In the notes , the author stated that when the force is applied through the centorid of cross section , the channel will bend and twist. but , on the second page , the author stated that the shear center lies on an axis of symmetry of member's cross sectional area... So, i am...
  14. F

    Direction of Shear Stress at the Edge: Why Do the Top and Front Planes Meet?

    Homework Statement In the notes , i noticed that the shear stress on the top plane and the front plane will 'meet together' at the edge . I don't understand it why the direction is like that . Homework EquationsThe Attempt at a Solution Is it possible for both the shear stress to become like...
  15. F

    Variation of shear stress at the rectangle cross section

    Homework Statement In the notes , I don't understand why the shear stress is maximum at the edge ( circle part) . Homework EquationsThe Attempt at a Solution I think it's wrong . Refer to another diagram attached , i found that the shear stress varies parabolically across the vertical length...
  16. F

    Calculating Shear Flow in a Hollow Beam: Understanding Mistakes in Dimensioning

    Homework Statement for shear flow at D , the Q = Ay , i tried another method , i gt 30000 , instead of 29750, why the ans is different from 29750? why can't i use this method( i break the shaded area into 3 parts ( as shown in figure) Homework EquationsThe Attempt at a Solution Q = Ay =...
  17. F

    Shear Stress: Examining the Discrepancy

    Homework Statement In the notes, the author stated that the shear stress is constant over the bottom face of the segment ... why in figure 7-4 , we can see that the shear stress varies ? Homework EquationsThe Attempt at a Solution Which is correct ? The red circled part or the figure ? [/B]
  18. kamhogo

    Shear: What would be the equation for ''pure'' torque?

    Homework Statement We had this elementary experiment in class. An aluminium rod is fixed at one end and at the other end you have a disk. You hand increasingly heavy weights on the disk and measure how much the rod shears (twists). We were asked to make a graph of the shear torque vs. angle of...
  19. F

    Shear stress at different points

    Homework Statement In this notes , i don't understand how the Q=(Ay) of the is considered ... Homework EquationsThe Attempt at a Solution I think the both Q at part C and part B should be = (60)(15)(mm^2) ... i have redrawn the structure , i am not sure whether it is correct or not... From...
  20. F

    Shear flow in thin wall members

    Homework Statement In the notes , I don't understand that flange is thin , and the top and bottom surface are free of stress , can someone help to explain please? Secondly , why the q' is assumed to be q ' throughout the flange is assumed to be 0 ? why are they stress free ? We could see that...
  21. F

    Shear stress at centroid vs other point

    [ Mod Note: moving this to Physics H/W ] Homework Statement for this question , I'm having problem with the shear stress at point E and shear stress at centorid. normally , the shear stress at the centoid will be maximum . But , in my working , I found that the shear stress at the centroid is...
  22. F

    Shear stress at particular point in beam

    Homework Statement In the example , I suspect the selected A (area) is wrong... From the notes , A' is the area of top (or bottom ) portion of the member cross sectional area . But , in the example , we could see that the selected area is located to the right of the point where shear stress is...
  23. C

    Shear stress in beam formula

    Homework Statement In this notes , why the shear force used is the 19.5kN ? Why not 6.5kN ? From what i know , the formula of shear stress is tau = VQ/ It , where V is the shear force ... There are two values of V in this question , why the larger one (19.5kN ) is chosen ?Homework EquationsThe...
  24. F

    Moment of inertia in shear stress formula

    Homework Statement In the first photo , i was told that the I represent the moment of inertia about the neutral axis ... But , in the 2nd photo , i found that the author calculate the moment of inertia about the x-axis (parallel to neutral axis ) and y -axis ( perpendicular to neutral axis) ...
  25. C

    Shear Force Diagram: 45N at 0.6m from B vs. 0.5m from D - Homework Question

    Homework Statement In this question , the 45N is acting at 0.6m from B ... why the author put the 45N forces at D in the shear force diagram ? Is it wrong ? Homework EquationsThe Attempt at a Solution IMO , the 45N should be put at 0.5m from D . Correct me if i am wrong
  26. MaxKang

    How is shear stress related to shear rate in aerodynamic applications?

    Hello everyone, I came across this in J. Anderson's book "Fundamentals of Aerodynamics". "For the type of gases and liquids of interest in aerodynamic applications, the value of the shear stress at a point on a streamline is proportional to the spatial rate of change of velocity normal to the...
  27. S

    I How to prove that shear transform is similarity-invariant?

    OK, my understanding is that the characteristic equation for a matrix is similarity-invariant, from which results that the trace & determinant - which correspond to the penultimate & free coefficients of the characteristic equation - and other parameters (corresponding to other coefficients) are...
  28. C

    Shear force diagram and bending moment diagram

    Homework Statement theoretically, bending moment should ends at bending moment = 0 , am i right ? Homework EquationsThe Attempt at a Solution Here's my sketch of SFD and BMD ,my bending moment doesn't return to 0 , which part of my working is wrong ... to find bending moment (M) , i get M...
  29. C

    Shear stress acting on an element

    Homework Statement When an element of material is subjected to pure shear stress , equlibrium requires that equal shear stress must be developed on four faces of an element . Homework EquationsThe Attempt at a Solution I can't understand the statement . I assume the 'element ' is cubic ...
  30. Sean Trainor

    What is shear stress on the Key

    Hi guys, I'm trying to work out the following: Assume uniform shear stress distribution across "Key" width. What is the shear stress (psi) on the "Key" at the interface with the "Shaft"? Torque (in-lb) = 4959 Shaft diameter (in) = 2 Key width/height (in) = 0.3 Key length (in) = 2
  31. C

    Calculating Shear Force: Understanding Two Forces Acting in Opposite Directions

    Homework Statement in this diagram , we could see two forces acted to left , one force acted to right , total of two forces acting to left = force acting to right . Homework EquationsThe Attempt at a Solution i'm wondering if the total of two forces on the left are not the same with the...
  32. C

    Calculating Shear Strain: σx / E and -vσy / E

    Homework Statement for the stress applied at x direction , the tensile strain εx should be = σx / E , right ? and for the tensile strain εy should be = -vσx / E , am i right ? Homework EquationsThe Attempt at a Solution I think so because in 1.7.1.3 , εy = σy / E - vσx / E , and εx = σx /...
  33. G

    2-Dimension structure with highest shear strength

    I am looking for any references about 2-dimensional lattice structures (ie hexagonal like graphine) that have the highest shear strength (or just resistance to distortion in the 2D plane). Does anybody have any good references for this?
  34. F

    Shaft radius from shear modulus

    Hi. I am trying to determine the size of a shaft for a motor I am designing. The thing is, I can't seem to find shear stress alone for steel. I can find shear modulus easy though... But I don't really know the angle of twist. I know torque and I am trying to figure out radius. Should I just...
  35. B

    Shear force in a frame due to torsion?

    The orange thing is a gear being turned by a motor, which is intended to move the frame the shaft is fixed to. I realize the applied torque is going to create support reactions, but I can't quite figure out how to calculate the needed material strength so that the frame won't shear. All helps...
  36. C

    Correct Shear Force and Bending Moment Diagrams for Beam Analysis

    Homework Statement There are 2 graphs in the notes , the first represent the shear force diagram , while the secon d one represent the bending moment diagram... In the notes , we can see that the gradient of the force per meter to the right of B is decreasing ... Homework EquationsThe Attempt...
  37. C

    Moment of inertia in shear stress

    Homework Statement In the question , the author calculated the Ixx and Iyy , but he used the greater value (Ixx) in the calculation to calculate the shear stress , why did he do so ? why the greater value is used ? Homework EquationsThe Attempt at a Solution
  38. C

    Allowable shear stress in bending

    Homework Statement I think the notes is wrong . in the notes , it's given that σ allowable > Mmax / Ze Homework EquationsThe Attempt at a Solution i think it should be σ allowable > Mmax < Ze , am i right ? How could the σ allowable > Mmax / Ze ? If σ allowable > Mmax / Ze , the beam will...
  39. C

    Sign convention of shear stress

    Homework Statement In the in the first image , it's shown that the shear stresses has positive sign, whereas in the second image e (circled blue part) has different sign convention,which is positive and negative, which is correct? Homework EquationsThe Attempt at a Solution IMO, the second...
  40. C

    Shear stress at boundary of wall = 0

    Homework Statement in the formula of shear stress τ = (V)(Q) / It , Q=Ay = first moment of inertia of area, the area can be located above(or bottom) at the point of interest) when the chosen point is at the wall(boundary) , why shear stress = 0? Homework EquationsThe Attempt at a Solution When...
  41. C

    Angle between principal stress and shear stress

    Homework Statement I know that an element that is subjected to max shear stress is 45 degree away from position of an element that is subjected to principal stress.I couldn't understand why the θ s= θ p -45 degree? Cant it be θ s= θ p +45 degree ? Homework EquationsThe Attempt at a Solution...
  42. C

    Understanding Shear Force: Uniformly Varying Load in Region EF

    Homework Statement I'm having problem of the shear force at the uniformly varying load at region EF... Why the shear force isn't -26 +(-30*4/2) at E? but -26 +(-30*4/2) at F?Homework EquationsThe Attempt at a Solution as we can see the force at region F is 0. the force due to uniformly varying...
  43. C

    Shear stress at different points

    Homework Statement in the formula of shear stress, t is the width of member's cross sectional area calculated about neutral axis. for τc , why t is 6.4 ? Why not 102.1 ? second question, why we have to consider that specific area? Cant we consider the (red) area? Homework EquationsThe Attempt...
  44. C

    Calculating Shear Stress: Choosing Between Ixx and Iyy for Point P

    Homework Statement i know that to calculate the shear stress, formula is τ= (V)(Q)/ (I)(t) So, why the author choose to use Ixx, but not Iyy for shear stress at P? Homework EquationsThe Attempt at a Solution IMO, we should done the question in 2 ways, which are by using Ixx and Iyy...
  45. C

    Finding shear and normal stress after rotation

    Homework Statement http://ocw.nthu.edu.tw/ocw/upload/8/256/Chapter_7-98.pdf refer to page 3 in the 2nd, 3rd pictures, i have problem of finding σx'Homework EquationsThe Attempt at a Solution why can't use the formula to find σs ? it's given that σx' = ( σx+ σy)(0.5) + (0.5)( σx- σy)cos2θ +...
  46. C

    Why is the direction of shear stress important in pure shear stress?

    Homework Statement In my book, I was told that when an element is subjected to pure shear stress, equalibrium required that equal shear stress must be developed on four sides of the element...these stresses must be direct toward or away from opposite corners of element.. Homework EquationsThe...
  47. F

    Shear Stress in Beams: Proof & Explanation

    Homework Statement where V = total shear force at the location in question; Q = statical moment of area; t = thickness in the material perpendicular to the shear; I = Moment of Inertia of the entire cross sectional area. based on this formula , the shear stress is max at the neutral axis of...
  48. C

    Calculating Shear Stress in Beams: V and A Formula

    Homework Statement in the old thread , i was told that The formula for calculating the shear stress is a beam is ##τ = \frac{V ⋅ Q}{I ⋅ t}## τ - shear stress V - shear force Q - first moment of area above the location where the shear stress is calculated. I - second moment of area for the...
  49. C

    Calculating Shear Stress: Understanding the Role of Y in Shear Force Diagrams

    Homework Statement Refer to the second photo , Q= Ay Does the author mean point P is at the center of the region (62.5mm x 100mm) ?The figure is not labelled well i am confused Homework EquationsThe Attempt at a Solution In the notes , I was told that y is the location of the shear stress is...
  50. Guidestone

    Bending moment in an axis doesn´t match

    Hey guys, first of all, this isn't a homework question, I just want to know why the results are what they are. I've been trying t obtain the same numbers using moment equilibrium but they still don't match. This is the example: W are the forces applied by the gears in force-pounds. The gears...
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